A pulse radar which searches for an object in a space by using a pulse wave basically has the configuration shown in FIG. 6.
Namely, a transmitting unit 11 receives a trigger signal G output at a predetermined cycle Tg from a control unit 20 which will be described later, by a pulse generator 12.
The pulse generator 12 outputs a pulse signal Pa with a predetermined width synchronous with a trigger signal G to a burst wave generating device 13.
The burst wave generating device 13 outputs a burst wave Pb having a carrier signal with a predetermined frequency in a period when a pulse signal Pa is being input (for example, in a period when a pulse signal Pa is being at a high level). In addition, the burst wave generating device 13 stops outputting a burst wave Pb having the carrier signal in a period when a pulse signal Pa is not input (for example, in a period when a pulse signal Pa is at a low level).
Note that examples of the configuration of the burst wave generating device 13 include a system in which a burst wave having a carrier signal with a predetermined frequency which is continuously output is made intermittent by a switch, and a system in which an oscillation operation of an oscillator oscillating a burst wave having a carrier signal with a predetermined frequency to output is controlled to be on/off.
A burst wave Pb output from the burst wave generating device 13 is amplified by a power amplifier 14, and is supplied to a transmitting antenna 15.
Therefore, a pulse wave Pt with a predetermined width which is synchronous with a trigger signal G is emitted into a space 1.
When the pulse wave Pt is reflected by the body 1a existing in the space 1, the reflected wave Pr is received by a receiving antenna 17 of the receiving unit 16, and a received signal R thereof is detected by a wave-detecting circuit 18.
A signal processing unit 19 analyzes the body 1a existing in the space 1 by determining a timing of a change in a level of a signal H output from the receiving unit 16, or an output waveform in, for example, a timing when a pulse wave Pa is transmitted from the pulse generator 12 of the transmitting unit 11 being as a reference timing.
The control unit 20 performs predetermined various controls onto the transmitting unit 16 and the receiving unit 11 based on processing results of the signal processing unit 19.
Note that a basic configuration of such a radar is disclosed in the following Patent Documents 1 and 2.
Pat. Document 1: Jpn. Pat. Appln. Kokai Publication No. 7-012921
Pat. Document 2: Jpn. Pat. Appln. Kokai Publication No. 8-313619
Radars for automobile use to be put into practical use in recent years among radars having such a basic configuration include two types of the following radars.
Pulse radars of the first type are radars aiming at support at the time of high-speed driving, such as collision prevention and driving control by searching for a narrow angular range at long range on high power using a millimeter waveband (77 GHz).
Pulse radars of the second type are short range radars aiming at support at the time of low-speed driving, such as dead zone assistance for automobile and assistance for putting a car in a garage by searching for a wide angular range at close range on low power using a quasi-millimeter waveband (22 to 29 GHz).
UWB radars using the quasi-millimeter waveband are used as, not only radars for automobile use, but also radars for walking support for visually impaired humans, close range communication system, and the like.
In broadband UWB radars, for example, a short pulse whose width is 1 ns or less can be used, which can realize a radar with a high range resolving power.